Air core drill



Jan. 10, 1956 J. LAMPRECHT 2,730,335

AIR CORE DRILL Filed March 16, 1953 2 Sheets-Sheet 1 Fig.

Joseph amprechf IN V EN TOR.

Ann @520. 3M

I Jan. 10, 1956 Filed March 16, 1953 Fig. 5

VIIIIIIIIIIIIIIIIIII/ 4 |lIlIIIIIllll Fig. 4

J. LAMPRECHT AIR CORE DRILL 2 Sheets-Sheet 2 Joseph Lamprech/ I N V EN TOR.

United States Patent@ AIR -CORE DRILL v Joseph Lamprecht, 'Fayettevill'e; N. Y. Application March 16, '1953, Serial-rNo;T342',545-" 4 Cla'imsr. (Cl; 255 72)? This invention relates in general-to-air core drills-for cutting sample cores, and more particularly to arr-air "core; a drill having means for disposingrof ithe debris. from v drilling.

A primary object of this invention is to provide a core drill assembly having means for disposing of thedebris from drilling in the dry state,-whereby*a' drilling opera- I tion may not be hampered by bad weather conditions.

Another object of this invention is to provide an improved cylindrical drill for-cuttingcores from material, said drill having means-supplying air undenzpressure to' the interior thereof wherebydust and particles formed by the drilling operation may be directly blown=out of,

the hole being drilled'by thecompressedair Another object of thisinvention is to provide an im-- proved core drill assembly said core drill assembly-id.- cluding a-snpportingibase;andacylindricalldrill, said sup'-- porting base having a fittingthereon for attachment'of an airline thereto, means communicating saidfitting with the interior of the cylindrical drill whereby air may be applied to the interior of the cylindrical drill'while disposed in the supporting base and'engagedi-n a drilling operation.

A further objectof thisinvention is to providean im-@ proved core drill assembly, said assembly-beingof relatively simple construction whereby-it may be economically manufactured.

With these objects definitely in :view,-this'invention.re-a

sides in certain novel features of construction,- combiner-vtionand arrangement of elements and portions as will-.be

hereinafter described in detail in thespecificatiompartiew '45 larly pointed out in the appended claims,and illustrated in the accompanying drawings whichiorma material part of this specificatiomand inwhichz s Figure 1 is a side elevational viewof theiaincore drill a assembly, whichis the subject of thisinventiom-thedrill:E

of the assembly beingillustrateddn its position priorto drilling into-a slab of material, on which its supportingbase is supported,-a proposed hole in the slab of shown in dotted 1ines;

material being Figure 2v is a transverse horizontal sectionalviewitaken substantially upon the plane indicated "by thefsect-ionsline 2-2 of Figure l and showingthe general relationship between a cylindrical drill and its supportingibase; 4

Figure 3 is a bottom plan ;view..of the core drillassembly of Figure 1, the cylindrical drillubeing in position witha in the limits of the supporting base;

Figure 4 is an enlargedttransverse vertical sectional viewtaken along the longitudinal axisrof .the-eoredrill assembly of Figure -1, the air motor for..rotating -the:cylindrical drill being broken vot'f and onlyathe bottonrchuck portion being illustrated;

Figure 5 is a fragmentarytransversevhorizontal sectional view taken substantially uponithe.plane indicatedby the section line 55 of Figure 4 and showing theflgeneral arrangement of passageways for the passing of air through i the'supporting baseinto'the interioiof the 'lcylindrlic'alt drill;

Figure 6 is an enlargedb'c attorn plan view'o'f thebylindrical drillrof Figures 1' through-5 and showing the general: arrangement'tof and construction of the cutting teeth 1 at the :lower end thereof; L

Figure 7 is an enlarged longitudinalveitical "sectional Patented Jan. 10, 1956 view of ihfivlOWl' portion of a modifiedform' of cylin-vdrical drill, the modified cylindricaldrill having a detach-i able cutting head threadedly engagedon the lower 'end' thereof;

Figure 8 is a bottom planview of the cuttinghead of Figure'fi and showing the general construction of thecutting teeth-formed thereon; and,

Figure9 is a sideelevational-view of the modified cutter head of Figure 7.

Similar. characters of reference designate similar or identical elements and portions throughout the specification and throughout theditterent'viewsof the drawings.

Referring now to the accompanying drawings in detail,

it will be seen that there is illustrated'in Figure 1 the complete air core drill assemblywhich includes a supporting base lllya cylindrical drill 12 rotatably mounted in the supporting base 10, and a conventional rotating air drill motor 14, as is disclosed in Patent No. 1,750,013, dated March 11, 1930, connected to the upper end of the'drill lzfor rotating same. The supporting base It) is engaged on the material 16 to be core drilled.

The supporting base Ill includes a circular base plate 18 which has integral therewith and projecting upwardly therefrom a concentric tubular portion 249- Also projectingupwardly from the upper surface of the basez plate 18 i is aplurality of reinforcing ribs 22extending between'the base plateslli and the tubular portion 20 in order to reinforce the connection between the tubular portion and the base plate.

As is best illustrated in Figure 4, the base plate 18 is provided with a depending-annular:fiange 24 along its outercircumferential. edge in order to reinforce same. It will be noted that the bottom of the annular flange 24 lies in the same horizontal plane as the bottom of thetubular portion 20 which projects below the main surface of thev base plate 15.v Extending radially from the bottom of the tubular portion 20 are reinforcing ribs 26 on the I underside of the base' plate 13. As is best illustrated in Figure- 3, the reinforcing-ribs 26 terminate at the annular flange 24tand are enlargedadjacent said annular fiangew Theienlarged-portion .of eachrib 26 is referred to by tion 34 and a 'solid upper portion 36. .The solid upper portion 36 'has integral therewitha concentric shank 38 which is of a conventional Morse taper and is illustrated g as being engaged in a portion of a chuck 40 carried by the air drill motor 14;

it will be understood that thechuck 40 tightly engagesathe tapered shank 38 of the" cylindrical drill 12in order to rotate-same.

Referring now to Figures4 and 6, in particular, it will be seen thattthebottom of the cylindrical drill 12 is enlargeclasy'mmetrically on each side of andrforrned to present a spaced cutting teeth 42, so a slab; 'etc., leaving vertical of the drill wall.

the main drill wall,

as to cut an annular hole in Eachcutting tooth 42 includes a forward cutting edge 44 at the-bottom of thetooth 42,- the' cutting edgefll being at an anglefto a ho'rizontalradialline through the"drilla?'tis, the":cutting edge 44 projecting equally both-inwardly and outwardly"of the""'cyliridrial annular spaces on each side plurality' of circumferentially l portion 34 of the drill 12, and forms with the latter a generally T-shaped cross-section, as is best illustrated in Figure 4. The portion of the tooth 42 to the rearward of the cutting edge 44 reduces symmetrically in radial thickness circumferentially, in a direction opposite to that of rotation, so as to equal the drill wall thickness at a point just forward of the next tooth 42 to the rearward, and the under surface of the back portion of each tooth 42 curves upwardly toward the next tooth 42, both of these taperings resulting in spaces between each pair of adjacent teeth 42, through which spaces the compressed air in the center of the drill 12 passes radially outwardly from the annular space between the inner surfaces of the annular hole being drilled and the'drill wall, to the annular space between the outer surfaces of the drill wall and the annular hole being drilled.

In order that the supporting base 19 may be easily transported, it is preferably formed of aluminum and, therefore, does not provide a suitable bearing surface for the cylindrical drill 12. The tubular portion 20 of the supporting base is provided with a concentric interior bearing sleeve 48 which is preferably formed of bronze. Since the cylindrical drill 12 has pressure applied thereon along a vertical axis only, it will be understood that the purpose of the bearing sleeve 48 is merely to guide the cylindrical drill 12 and restrain same against any movement from a position concentric with the center line of the hole being drilled.

During the normal drilling of a hole to obtain a core, the cutting teeth 42, which are formed of a hardened material, will cut the slab 16 and form dust and small particles of material. Inasmuch as the dust and small particles of material hinder the drilling operation and should be disposed of, it is the purpose of this invention to provide means for disposing of said dust and drilling particles without utilizing fluids. Inasmuch as a compressed air source is required for the air drill motor 14, it is the intention of this invention to utilize said compressed air source for directly blowing the dust and particles formed by the drilling operation out of the hole being drilled. Therefore, the tubular portion of the supporting base 10 is provided adjacent its upper end with a radial bore 50 which is internally threaded and adapted to have threadedly engaged therein an air line fitting 52. Extending radially through the upper portion of the bearing sleeve 48 and in alignment with the bore 50, is a bore 54. Formed in the interior surface of the bearing sleeve 48 in vertical alignment with the bore 54 is a horizontally disposed annular groove 56 which communicates with the air line fitting 52 through the bores 50 and 54. Communicating with the annular groove 56, in the bearing surface of the bearing sleeve 48 and extending vertically downwardly therefrom is a plurality of spaced longitudinal grooves 58 for supplying air throughout the length of the bearing sleeve 48. However, it will be noted that the longitudinal grooves 58 terminate short of the lower end of the bearing sleeve 48 in a horizontally disposed annular groove 59, and air is prevented from escaping at the bottom of the grooves and air is also prevented from escaping from the inner faces of the grooves by the cylindrical portion 34 of the cylindrical drill 12.

In order that air under pressure may be supplied to the hole being drilled, it is necessary that the interior of the cylindrical bottom portion 34 of the cylindrical drill 12 be communicated with the grooves formed in the bearing surface of the bearing sleeve 48. Therefore, the upper end of the cylindrical portion 34 has a horizontally disposed annular groove 60 formed in its outer surface, the annular groove 60 communicating with the plurality of axial bores 62 extending through the side wall of the cylindrical portion 34. When the cylindrical drill 12 is in its uppermost position, the annular groove 56 in the bearing sleeve 48 is in vertical alignment with the annular groove 60 in the cylindrical drill 12 and air passes through the bore 54 from the air line fitting 52 into the annular groove 56, from the annular groove 56 into the annular groove 60, and then into the interior of the cylindrical bottom portion 34 through the bores 62 therethrough. As the drilling operation proceeds, the cylindrical drill 12 moves downwardly in the bearing sleeve 48 and the annular groove 60 moves out of vertical alignment with the annular groove 56. Air is then supplied to the annular groove 60 through the longitudinal grooves 58 after passing into the annular groove 56.

Referring now to Figure 1, in detail, it will be seen that there is illustrated a main first air supply line 64 which is provided with a T-fitting 66. Extending from one connection of the T-fitting 66 is an air supply line 68 which is connected to a fitting 70 on the air drill motor 14. Extending from the other connection of the T-fitting 66 is an auxiliary air line 72 which through conventional pipe fitting 74 is connected to the air line fitting 52 for supplying air to the tubular portion 20 of supporting base 10. During a drilling operation, as the cylindrical drill 12 is rotated by the air drill motor 14 and moved downwardly into the slab 16 in response to pressure applied thereto and as a result of the cutting of the cutting teeth 42, dust and particles of material are formed from the drilling. Inasmuch as the hole being drilled is of a larger width than the thickness of the cylindrical lower portion 34 of the cylindrical drill 12 above the tooth level, air will be permitted to pass downwardly between the inner surface of the cylindrical portion 34 and a core being cut, the core being illustrated by dotted lines in Figure l and referred to in general by the reference numeral 76. Compressed air then further passes downwardly between the core 76 and the drill 12 at the rear of each of the cutting teeth 42 just in front of the cutting edge 44 of the next cutting tooth 42. After the compressed air has reached the bottom of the hole being drilled, it passes outwardly radially through the spaces 46 formed in the underside of the drill 12 and moves upwardly between the outer surface of the cylindrical portion 34 and the outer cylindrical surface of the hole being drilled to the top of the hole being drilled. The swift movement of the compressed air past the cutting edges 44 of the teeth 42 results in the carrying of the dust and small particles of material outwardly and upwardly of the hole simultaneously with their forming.

The novel construction of the supporting base 10 and the cylindrical drill 12 permits the use of compressed air to remove the dust and particles without the use of a liquid. By utilizing compressed air only to remove the dust and particles formed by drilling, it will be readily apparent that the air core drill, which is the subject of this invention, may be utilized in all types of weather conditions. Therefore, it is obvious that the improved core drill overcomes an objection of the commonly used core drills in that it does not utilize water or other liquids for removal of the dust and particles formed in drilling, thus eliminating the difliculties encountered in low temperatures due to the freezing of the water.

Referring now to Figures 7, 8, and 9 in particular, it will be seen that there is illustrated a modified form of cylindrical drill, this cylindrical drill being referred to in general by the reference numeral 78. The cylindrical drill 78 has a cylindrical lower portion 80 which is provided with an annular recess 82 adjacent its lower end, and the lower end thereof is externally threaded as at 84. Threadedly engaged with the threaded portion 84 of the cylindrical drill 78 is a removable cutter head which is referred to in general by the reference numeral 86. The cutter head 86 is provided with suitable spanner wrench openings 87 to facilitate removal.

It will be noted that the removable cutter head 86 is recessed at its upper end and internally threaded to provide threads 88 which interengage with the threads 84 of the cylindrical drill 78. The removable cutter head 86 is generally of an inverted T-shape cross-section and has hardened teeth 90 formed at the lower end of same, the teeth having cutting edges 92. Each tooth 90 tapers upwardly rearwardly of the cutting edge 92 thereof towards the next tooth 9d to form a space 94 just in front of the cutting edge 92 of the next tooth 90. In order that the dust and particles formed by drilling may pass upwardly around the cutter head 86, the enlarged portion of the cutter head is provided with a plurality of vertically extending spaces 96 which are generally in alignment with the transversely extending spaces 94.

it will be understood that the cylindrical drill '78 is intended as a replacement for the cylindrical drill l2 and is formed at its upper end (not shown) with a solid portion having a concentric shank extending upwardly therefrom for engagement with the chuck 40 of the air drill motor 14. It will be understood that the diameter of the cylindrical drill 78 is the same as the cylindrical drill l2 and is intended to be utilized in combination with the supporting base it By utilizing a removable cutter head, such as the cutter head 86, it is not necessary to replace the entire cylindrical drill upon the breaking or the dulling of the cutting teeth.

inasmuch as the different forms of tools utilized with the base it) require difierent spacings between the face and the material being drilled, it may be necessary to vary the length of the pins 32 to properly initially seat the base 10 on the surface to be core drilled.

The operation of this device will be understood from the foregoing description of the details thereof, taken in connection with the above recited objects and drawings. Further description would appear to be unnecessary.

Minor modifications of the device, varying in minor details from the embodiment of the device illustrated and described here, may be resorted to without departure from the spirit and scope of the invention, as defined in the appended claims.

Having described the invention, What is claimed as new is as follows:

1. A core drill for cutting cylindrical samples from rock, tile, cementitious and other materials, said core drill comprising a cylindrical drill having cutting teeth at the lower end thereof, a supporting base for said cylindrical drill adapted to overlie the surface of the material to be drilled, said cylindrical drill being mounted in said supporting base for rotation and for axial movement therethrough, an air line attachment carried by said supporting base, passage means in said supporting base and cylindrical drill in communication with said air line at tachrnent for delivering air to the interior of said cylindrical drill, said cylindrical drill having a cylindrical main wall portion, said cutting teeth being circumferentially spaced and projecting inwardly and outwardly of said main wall portion of said cylindrical drill to provide clearance on each side of said main wall portion when disposed in a hole drilled by said cutting teeth, said cutting teeth having areas of reduced width providing vertically extending recesses along both the outer and inner peripheries thereof, each of said recesses terminating at the forward edge of the next tooth, the cutting teeth having cutting edges circumferentially spaced to provide axially extending recesses intersecting said vertically extending recesses whereby air applied to the interior of said cylindrical drill will be free to pass downwardly through said drill and upwardly out of a hole being drilled.

2. A core drill for cutting cylindrical samples from rock, tile, cementitious and other materials, said core drill comprising a cylindrical drill having cutting teeth at the lower end thereof, a supporting base for said cylindrical drill adapted to overlie the surface of the material to be dril ed, said cylindrical drill being mounted in said supporting base for rotation and for axial movement therethrough, an air line attachment carried by said supporting base, air passages in said supporting base and cylindrical drill for delivering air to the interior of said cylindrical drill, said supporting base being provided with an internal longitudinally extending bearing surface guidingly engaging the exterior of said cylindrical drill, said air passages including a plurality of longitudinally extending grooves formed in said bearing surface, an annular groove at the upper ends of said longitudinal grooves communicating same, a bore through said supporting base and said bearing surface communicating said air line attachment with said annular groove for supplying air thereto, said passages in said cylindrical drill being communicated with said grooves.

3. The core drill of claim 2 wherein said air passages in said cylindrical drill include a plurality of bores through said cylindrical drill, an annular groove in the outer surface o-f said cylindrical drill communicating said bores, said annular groove being disposed within said supporting base and communicating with the longitudinal grooves in the bearing surface.

4. The core drill of claim 2 wherein said bearing surface is a portion of a bearing sleeve disposed in said supporting base.

References Cited in the file of this patent UNITED STATES PATENTS 286,599 Fitzgerald Oct. 16, 1883 895,228 Bartlett Aug. 4, 1908 2,201,270 McIntyre May 21, 1940 2,228,373 Slater Jan. 14, 1941 2,301,478 Tibbals, J12, et a1. Nov. 10, 1942 

